Pressure release devices



March 27, 1962 H. c. FOSTER 3,026,800

PRESSURE RELEASE DEVICES Filed Aug. 21, 1959- 2 Sheets-Sheet 1 INVENTOR. HARRY CLARK FOSTER A 7'TORNEY March 27, 196 H. c. FOSTER 3,026,800

PRESSURE RELEASE DEVICES Filed Aug. 21, 1959 2 Sheets-Sheet 2 g 2/ raw 2% f 53 1 z 44 f? E V 6 1% f 1 so 7 I l ig 25 2/ 25 E I5- 2 1 13 v w 1? /l r INVENTOR.

HARRY CLARK FOSTER A TTQRNE United States Patent M 3,026,800 PRESSURE RELEASE DEVICES Harry Clark Foster, East Alton, Ill., assignor to Olin Mathieson Chemical Corporation, East Alton, lll., a corporation of Virginia Filed Aug. 21, 1959, Ser. No. 835,257 3 Claims. (Cl. 102-25) This invention relates to pressure release devices and more particularly to such devices adapted to effect the sudden release of a charge of compressed gas to serve as a work performing medium. While such devices are applicable to many commercial applications, the present invention will be described with particular reference to blasting cartridges utilizing a gas under pressure.

Material breaking cartridges using compressed gas to execute the required work are well known and widely used in the mining industry. Such cartridges or blasting devices are all reliant upon the sudden release of compressed gas to give a quasi explosive effect. The predecessors of this type of blasting cartridges consisted essentially of a cylindrical gas-containing cartridge having venting means. The cartridges were charged with gas under considerable pressure, sealed and then conveyed to the face to be worked. The compressed gas within these cartridges was released by elaborate remote control means. More recently, the practice has been to place an uncharged cartridge in the bore hole and pump gas through a suitable conduit into the cartridge in situ. Conventionally, these cartridges are formed of high strength materials and are provided with a relatively Weak member which shears or ruptures so as to liberate the gas from the cartridge body. Since the amount of pressure that can be built up in the cartridge body is dependent upon the strength of the expendable member, the quantity of energy developed by the liberation of the gas can be controlled within relatively close limits. Such cartridges are generally satisfactory but have one serious inherent drawback. After each shot, the discharge end of the cartridge must be dismantled to remove the expendable portion which has ruptured or sheared and to replace it with a new one.

This shortcoming has been well recognized and has led to a concerted effort for the development of automatic shells. While many so-called automatic shells have been presented, they have met with only a modicum of success. The previous types of automatic cartridges are operable, but they are very heavy, complex and unreliable. Although the expendable portions of the shell have been eliminated, this elimination has introduced new and more serious problems. Normally, the known automatic shells rely upon a series of two or more control or pilot valves to initiate the main release valve. Such complexity of design leads to cartridges that are difiicult to control and exceedingly difiicult to discharge at a desired predetermined pressure. In addition, the great number of moving parts in the automatic shells prior to the advent of the present invention has confronted the industry with a formidable sealing problem.

Therefore, it is an object of this invention to provide new and improved automatic or semi-automatic gas liberating devices. A further object is to provide a device of this character having novel gas release means. Another object of this invention is to provide a simplified manual, automatic or semi-automatic material breaking shell overcoming the disadvantages of the prior art.

The manner in which these and other objects are achieved will be apparent from the following specification together with the drawing in which:

FIGURE 1 is a longitudinal sectional view of a blasting device illustrating an embodiment of the present invention;

3,026,800 Patented Mar. 27, 1962 FIGURE 2 is a similar view of the device of FIG- URE 1 in open position;

FIGURE 3 is a longitudinal sectional view of a blasting device illustrating another embodiment of the present invention; and

FIGURE 4 is a longitudinal sectional view illustrating still another embodiment of the present invention.

The same numbers are used throughout the various figures of the drawing to identify similar components.

Referring to FIGURE 1, an elongated tubular body formed of metal, reinforced plastic or other material of a strength to contain gas under high pressures, for example, 6,000 to 20,000 pounds per square inch, is indicated generally at 1. Suitable means, not shown, are provided at one end of the cartridge for introducing compressed gas into it. The outer diameter of the body is such that it may be set freely within a bore drilled in the face of the material to be mined. The end of the body remote from the gas inlet terminates in a sleeve 2 which is screw threadedly attached to the body as shown at 3. The seal between these two members is completed by an annular resilient sealing means, such as -O-ring 4. The other end of the sleeve 2 is screw threadedly attached to end cap 5 which serves to retain valve body 6. An annular extension 7 of the valve body cooperates with the sleeve to form an annular slot 8 in which main valve 9 is slidably maintained. It will be noted that the main valve is sealed to the annular projection 7 of the main valve 6 by a pair of O-rings 10 and 11. The valve is normally urged to a closed position spanning the ports 12 by helical spring 13 positioned in the annular slot. Lateral ports 12 are aligned with cooperating vents 14 in annular projection 7 of the valve body. The sliding fit between the annular projection 7 of the valve body 6 and sleeve 2 is sealed by O-ring 24.

The valve body contains control valve 15 which is normally urged to close orifice 16 by control spring 17. The chamber 18 containing the control valve is also provided with one or more radial passageways 19 in communication with an annular space 20 positioned about the valve body and closed at one end by the main valve 9. The control spring 17 is adjustable by means of set screw 21 in cooperation with spring support 22. Set screw 21 is held in place by lock nut 23.

In operation, compressed air or other suitable gas is introduced into main chamber 25 through a suitable gas inlet. During charging, control valve 15 is in a closed position as shown in FIGURE 1. This valve, in cooperation with O-rings 10, 11 and 24 serve to maintain the compressed gas charge completely within the main chamber 25. In this way, the annular slot 8 is substantially at atmospheric pressure during charging and any tendency toward a pressure increase in the slot is overcome by air leakage between sleeve 2 and valve 9.

When the discharge pressure is attained in main chamber 25, the pressure urges control valve 15 out of sealing relationship with orifice 16 in the valve body 6. At this point, the effective area of the control valve 15 is substantially and suddenly increased and forces the control valve back against control spring 17 exposing radial passageways 19. A portion of the compressed gas in the main chamber then passes through orifice 16, radial passageways 19 and annular space 20, forcing main valve 9 against helical spring 13 and exposing ports 12 and vents 14. When the vents are thus partially opened, the sliding valve moment is augmented by the compressed gas in the main chamber acting through the vents. The compressed gas in main chamber 25 is thus rapidly and efiiciently liberated from the main chamber.

In FIGURE 2, the control valve 15 and main valve 9 are shown in an open position. This represents the condition of the cartridge at the time of discharge. After the charge of gas has been dumped from main chamber 25, control valve is returned to its original position by control spring 17. In like manner, control valve 9 is returned to a closed position by helical spring 13. Any tendency for a build-up of pressure in annular space after discharge is readily overcome by the dissipation of the pressure between sleeve 2 and main valve 9. Thu-s, the embodiment of FIGURE 1 is fully automatic and is returned to firing condition after each discharge.

The embodiment shown in FIGURE 3 represents a modification of the example shown in the previous figures. As will be noted, the control valve is of substantially the same type used in FIGURE 1. However, the annular extension 7 of the valve body 6 has been eliminated and the main valve 9 is provided with an internal annular flange 26. Also, the body 1 has been extended internally as shown generally at 27 and is provided with shoulder 28 which forms a support for helical spring 13. It will be noted in this embodiment that the main spring 13 is positioned within the main chamber rather than in annular slot 8 and the seal between projection 27 and the main valve 9 is provided by O-ring 29. Thus, here again, the annular slot 8 is maintained substantially at atmospheric pressure throughout the operation of the cartridge.

The operation of this embodiment is substantially the same as that described above with relation to the embodiment of FIGURE 1. This embodiment is also completely automatic and after the shell is fired by control valve 15 being depressed so as to permit passage of air through radial passageways 19 and annular space 20, the control valve 15 and main valve 9 are returned to their original positions by springs 17 and 13, respectively.

The embodiment illustrated in FIGURE 4 employs substantially the same control valve mechanism as described above. In this example, annular space 20 is formed between sleeve 32 and valve body 6 which are screw threadedly attached. This embodiment differs from those of FIGURES 1 and 3, however, primarily in that the annular slot 8 is maintained at substantially the same pressure as main chamber 25 by means of one or more vents 30. Also, a portion of the main valve 9 at the end remote from the annular slot 8 is also subjected to the pressure of the main chamber because of passage of compressed gas into annular groove 31 about the base of the main valve. However, the effective area of the main valve in slot 8 is greater than its effective area in annular groove 31. Thus, during charging of the main chamber 25 the main valve 9 is forced into sealing position with valve body 6 with progressively increasing force. When the predetermined discharge pressure is attained, control valve 15 is depressed as in the previous embodiments and a portion of the gas in the main chamber passes through orifice 16, radial passageways 19, and into annular space 20. Since the efiective area at the base of valve 9 in contact with annular space 20 and annular groove 31 is much greater than the effective area of the valve in slot 8, the main valve is rapidly forced to an open position and the gas is suddenly and efiiciently discharged through vents 14 in the annular projection 7 of valve body 6. This action of the valve is particularly rapid because all springs in association with the main valve have been eliminated.

This cartridge is not automatic and is designed to be manually returned to firing position. Thus, after the cartridge is fired, the main valve 9 remains open. It is easily closed, however, by manually pushing it into a closed position. This is readily accomplished by means of annular protuberance 33 on the valve. After the valve is thus reset, the cartridge is in condition to be refired.

While the invention has been described with particular reference to blasting or coal breaking cartridges, it will be readily appreciated that it is also applicable to any pressure release device in which a charge of compressed gas is suddenly liberated to act as a work performing medium. Such devices include metal working and shaping devices, cutting devices, power cartridges, and the like.

Although the invention has been described in considerable detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that many modifications can be made without departing from the spirit and scope of the invention.

What is claimed is:

1. In an apparatus for liberating explosively a charge of compressed gas as a work performing medium,

(a) a cylindrical body having a wall,

(b) a pressure chamber positioned within said wall to form an annular space between said wall and said pressure chamber,

(1) said wall having at least one exhaust port to provide communication between said annular space and the atmosphere,

(2) said pressure chamber having venting means to provide communication between said pressure chamber and said annular space,

(c) a first valve means comprising a sleeve positioned in said annular space in sliding contact with said wall and said pressure chamber, said sleeve being movable (1) from a closed position in which communication between said annular space and the atmosphere, and between said annular space and said pressure chamber is cut off,

(2) through a partially open position in which communication between said annular space and the atmosphere is cut off while permitting communication through said venting means between said pressure chamber and said annular space,

(3) to an open position where communication between said pressure chamber and said annular space and between said annular space and the atmosphere is elfected,

(d) a second valve means communicating with said pressure chamber and said annular space, said second valve means permitting fluid pressure derived from said pressure chamber to be applied to the cross-sectional area of said sleeve to move said sleeve slowly from the closed position to said partially open position, whereby (1) augmenting fluid pressure passes from said pressure chamber through said venting means to said cross-sectional area of said sleeve, applying a secondary thrust to said sleeve, moving it sharply to said open position, and

(2) the charge of compressed gas from said pressure chamber is explosively released through said venting means to said annular space through said exhaust port to the atmosphere.

2. The apparatus of claim 1 wherein said venting means is a plurality of pressure chamber exhaust ports.

3. The apparatus of claim 1 wherein a helical spring means acts upon said sleeve to force said sleeve to the normally closed position.

References Cited in the file of this patent UNITED STATES PATENTS 2,083,697 Dull June 15, 1937 2,318,962 Parker May 11, 1943 2,420,370 Hamilton May 13, 1947 2,781,053 Berninger et al. Feb. 12, 1957 FOREIGN PATENTS 1,020,842 Germany Dec. 12, 1957 

